<html>
<head>
    <meta charset="utf-8">
    <style>
        #conatiner{
            width:400px;
            height:500px;
            border:1px solid #eee;
            position: relative;
        }
    </style>
</head>
    <body>
        <span>typing</span>
        <div>
             <span id="score">0</span>得分
        </div>
        <div id="conatiner">
            
        </div>
        <button id="start">开始游戏</button>
    </body>
    <script>
        var gamePad = {
            1 : {
                speed : 100
            },
            2 : {
                speed : 90
            },
            3 : {
                speed : 70
            },
            4 : {
                speed : 40
            },
            5 : {
                speed : 20
            }
        }
        var getRandom = function() {
            //随即一个97到122的字符;
            var charCode = 97+Math.floor(Math.random()*26);
            var speed = Math.ceil(Math.random()*4);
            return {
                code : String.fromCharCode(charCode),
                speed : speed,
                y : 0,
                x  : Math.floor(Math.random()*390),
            }
        };
        function game( n , score ) {
            var eConatiner = document.getElementById("conatiner");
            var eScore = document.getElementById("score");
            var showArr = []; //字符对象的列表
            var shoted = 0;
            //随机一个字符对象， 包含了字符的运动速度，字符的值
            //让showArr这个数组的数据运动;
            var run = function() {
                //随机生成字符对象
                if(Math.random()>0.9) {
                    var obj = getRandom();
                    showArr.push(obj);
                }
                //让元素运动
                for(var i=0 ;i < showArr.length; i++) {
                    showArr[i].y+=showArr[i].speed;
                    if(showArr[i].y>500) {
                        //showArr.splice(i,1);
                        clear();
                        alert("游戏失败");
                        location.reload();
                    }
                }
                eConatiner.innerHTML = "";
                //让元素添加到界面中;
                for(var i=0 ;i < showArr.length; i++) {
                    var eSpan = document.createElement("span");
                    eSpan.style.position = "absolute";
                    eSpan.innerHTML = showArr[i].code;
                    eSpan.style.left = showArr[i].x;
                    eSpan.style.top = showArr[i].y;
                    eConatiner.appendChild(eSpan);
                }
            }
            var keyup = function(ev) {
                for(var i=0 ;i < showArr.length; i++) {
                    if(showArr[i].code === ev.key || String.fromCharCode(ev.keyCode).toLowerCase() == showArr[i].code) {
                        showArr.splice(i,1);
                        shoted++;
                        eScore.innerHTML = shoted;
                        if(shoted === score && gamePad[n+1] === undefined) {
                            alert("少侠你好厉害， 你好快， 真的好快好快的");
                        }else if(shoted === score) {
                            clear();
                            alert("进入下一关");
                            game(n+1, score+10)
                        }
                        return;
                    }
                }
            }
            var clear = function() {
                clearInterval(game.timer);
                window.removeEventListener("keyup", keyup);
            }
            window.addEventListener("keyup", keyup);
            game.timer = setInterval(run,gamePad[n].speed);
        }
        document.getElementById("start").addEventListener("click", function() {
            game(1, 10);
        });
    </script>
</html>
　　